Fan hub



, Sept. 19, 1967 H. R. CRANE FAN HUB Filed March 4, 1966 Z W 7 N NE 4 av 5 V5 H United States Patent 3,342,273 FAN HUB Herbert R. Crane, St. Louis County, Mo., assignor to Emerson Electric C0,, St. Louis, Mo., a corporation of Missouri Filed Mar. 4, 1966, Ser. No. 531,908

4 Claims. (Cl. 170160.53)

This invention relates to motor-driven fans and particularly to hub means for attaching a fan to a driving shaft.

An object of the invention is to provide a particularly simple and inexpensive means for attaching a circular metal fan to a driving shaft.

A further object is to provide hub means for attaching a circular metal fan to a driving shaft, which hub I is constructed of a material which minimizes the transmission of vibrations between the driving shaft and fan thereby reducing the noise level of relatively high speed, motor-driven fans.

Further objects and advantages will appear from the following description when read in connection with the accompanying drawing.

In the drawing:

FIG. 1 is a front view of a fan having a hub constructed in accordance with the present invention;

FIG. 2' is a sectional view taken on line 2-2 of FIG. 1;

FIG. 3 is a plan view of the hub shown separately;

FIG. 4 is a side elevational view of the hub shown separately;

FIG. 5 is an enlarged sectional viewtaken on line 5 -5 of FIG. 1;

FIG. 6 is an enlarged sectional view taken on line 66 of FIG. 5;

FIG. 7 is an enlarged sectional view, similar to FIG. 6, showing a second form of retaining spring; and

FIG. 8 is a plan view of a sheet metal fan without the hub, showing the central perforation therein to receive the hub.

Referring to the drawing, a sheet metal fan is generally indicated at 10 having radially extending, articulated blades 12 and a central portion 14 having a central, circular perforation 16 therein including diametrically opposed re-entries 18 in the wall defining the perforation (see FIG. 8).

Inserted into the perforation 16 in fan 10 is a hub generally indicated at 20. Hub 20 has a flange 22 which bears against one side of fan 10 and a hollow, generally cylindrical portion 24 which extends through the perforation 16 and projects from the opposite side of the fan. The hollow, cylindrical portion 24 of the hub has a somewhat enlarged and tapered intermediate section 26 which increases in size inwardly toward the flange 22 and reduced diameter sections 28 and 30 at the outer and inner ends, respectively, of section 26 forming shoulders 32 and 34, respectively.

The hub 20 has a D-shaped, axial bore 36 adapted to receive a drive shaft 38 having a D-shaped, cross-sectional configuration. The flat side 40 forming the D-shaped portion of shaft 38 extends inwardly from the end of the shaft a distance equivalent to the length of hub 20, and a square shoulder 42 is formed at the termination of the flat side 40 which limits the inward movement of hub 20 on the shaft. The drive shaft 38 is provided with an annular groove 44 near its outer end which receives one leg of a retaining spring 46 formed of round wire, and the hub 20 is further provided with a transverse slot 48 extending inwardly from its outer end. The slot 48 permits the transverse insertion of the straight leg 47 of spring 46 into and through annular groove 44 in shaft 38.

The retaining spring 46 is formed of round wire having a straight leg 47, a formed leg 49, and a bight joining the legs. In its free form, the legs 47 and 49 are closer to each other than shown, so that when the retainer spring 46 is assembled in the position shown in FIGS. -1, 5, and 6, with the straight leg 47 inserted in groove 44 in drive shaft 38 and formed leg 49 snapped over the outer surface of the hub portion 28, it acts to press the fiat surface of shaft 38 against the flat wall of D- shaped bore 36 as well as keying the hub against outward axial movement on shaft 38. The radial depth of annular groove 44 in shaft 38 is somewhat less than the diameter of the round wire of which retaining spring 46 is formed, so that when inserted in groove 44, a portion thereof extends radially outward from the shaft. One wall of transverse slot 48 is spaced outwardly slightly from the Wall of bore 36 to accommodate the leg 47 of the retainer spring. The bottom of transverse slot 48 will therefore engage the leg 47 of the spring retainer to prevent outward movement of the hub 20 on shaft 38.

A second form of retainer spring 50 formed of round wire is shown in FIG. 7. This form of retainer spring has a straight leg portion 51 which is received in groove 44 of drive shaft 38, an arcuate portion 52 which bears transverse slot 48 in the end of the hub. Retainer spring 50 has such free form as to also urge the flat surface of drive shaft 38 against the flat wall of D-shaped bore 36 as well as'to key the hub against outward axial movement on the drive shaft.

Hub 20 is further provided with a opposed driving bosses 54 are received in the re-entries 18 of perforation 16 in the fan blade 10. These driving bosses prevent any relative angular motion of the fan 10 and hub 20. The hub 20 is constructed of a plastic material which has suflicient rigidity for the purpose and suflicient elasticity to recover from a substantial deformation upon assembly into the perforation 16 of the fan blade.

The diameter of the tapered hub portion 26 at the shoulder 34 is sufficiently larger than the diameter of circular perforation 16 to provide an adequate shoulder 34 to insure retention of the hub in the fan. The driving bosses or keys 54 are also somewhat larger than the reentries 18 in perforation 16 to insure against any slight relative angular movements of the hub and fan, and the axial spacing of the adjacent face of the flange rim with respect to shoulder 34 is somewhat less than the thickness of the sheet metal fan so that some distortion of the flange occurs when the hub is pressed into the aperture 16 to the shoulder 34.

The hub 20 is preferably formed by molding a plastic material having the desired physical properties. By way of example, a polypropylene thermoplastic having a Rockwell hardness of to (D785-A.S.T.M.) has been found to be a suitable material for the purpose. It has suflicient elasticity or memory to permit the deformation with recovery required to securely fix the hub in the metal fan and maintain this secure attachment. This material, as well as other plastic materials of this general character, is also highly effective in damping and minimizing the transfer of vibrations bewteen a motor drive shaft and fan blade in relatively high speed, motor-driven fans when formed as a fan hub in accordance with the present invention.

The foregoing description is intended to be illustrative and not limiting, the scope of the invention being set forth in the appended claims.

I claim:

1. In a device of the class described, a driven member having a generally circular perforation therein with repair of diametrically ntries in the wall forming said perforation, a hollow hub armed of resilient material mounted in said aperture and omprising a round tapered portion extending outwardly rom one side of said driven member, a flange on the ther side of said driven member, and a short cylindrical 'ortion having substantially the same diameter as said .perture entered in said aperture, said round tapered porion being of larger diameter than said aperture at its end tdjacent said one side of said driven member and diminishng outwardly to a diameter smaller than said aperture, vhereby a shoulder is formed on said hub at said one side )f said driven member, radial driving portions formed on aid hub extending longitudinally from said flange and )assing through said aperture wall re-entries in close fit 'elationship, said short cylindrical hub portion being .onger than the thickness of said driven member, and said iange having a circumferential rim projecting from the ,nner face thereof and engaging said other side of said iriven member, said hollow hub having sufficient resilience to permit passing said round tapered portion thereof through said aperture without permanent deformation thereof and said circumferential rim extending sufiiciently from the inner face of said flange to result in some distortion of said flange whereby said shoulder and said circumferential rim bear firmly against the opposite sides of said driven member.

2. In a device as set forth in claim 1 in which said hub has a non-circular longitudinal bore therethrough adapted to receive a non-circular drive shaft portion.

3. In a device as set forth in claim 1 in which said driven member is a sheet metal fan.

4. A device as set forth in claim 1 in which said hub further includes a short cylindrical portion at the outer end of said tapered portion which is smaller in diameter than the small outer end of said tapered portion whereby an external shoulder is formed, in which said hub has a through bore of D-shaped, cross-sectional configuration in which a round drive shaft having a D-shaped end portion and a circumferential groove formed therein near the outer end of its D-shaped portion is entered into said hub bore with the segmental shoulder formed at the inner end of its D-shaped portion bearing against said hub flange and with the inner edge of its circumferential groove in substantial alignment with said external shoulder, in which a part of said short cylindrical hub portion is cut away to provide access to an arcuate portion of said circumferential shaft groove opposite the flat side of said shaft and to further provide a transverse surface extending tangential to said arcuate groove portion and said transverse surface being in substantial alignment with said external shoulder and the inner surface of said circumferential shaft groove, and which further includes a spring element formed of spring wire having a straight key portion lying tangential to and in said arcuate portion of said circumferential groove, and having a second portion bearing against the exterior surface of said short cylindrical hub portion and against said exterior shoulder, and said spring element having such free form as to bias the flat surface of said shaft against the fiat surface of said bore.

References Cited UNITED STATES PATENTS 1,398,020 11/1921 Holley 287-53 X 2,702,087 2/ 1955 Beier -173 2,772,034 11/ 6 Richmond.

2,900,202 8/ 1959 Thompson 287-5204 3,302,867 2/ 1967 Roffy 170-16054 CARL W. TOMLIN, Primary Examiner. A. V. KUNDRAT, Assistant Examiner. 

1. IN A DEVICE OF THE CLASS A DRIVEN MEMBER HAVING A GENERALLY CIRCULAR PERFORATION THEREIN WITH REENTRIES IN THE WALL FORMING SAID PERFORATION, A HOLLOW HUB FORMED OF RESILIENT MATERIAL MOUNTED IN SAID APERTURE AND COMPRISING A ROUND TAPERED PORTION EXTENDING OUTWARDLY FROM ONE SIDE OF SAID DRIVEN MEMBER, A FLANGE ON THE OTHER SIDE OF SAID DRIVEN MEMBER, AND A SHORT CYLINDRICAL PORTION HAVING SUBSTANTIALLY THE SAME DIAMETER AS SAID APERTURE ENTERED IN SAID APERTURE, SAID ROUND TAPERED PORTION BEING OF LARGER DIAMETER THAN SAID APERTURE AT ITS END ADJACENT SAID ONE SIDE OF SAID DRIVEN MEMBER AND DIMINISHING OUTWARDLY TO A DIAMETER SMALLER THAN SAID APERTURE, WHEREBY A SHOULDER IS FORMED ON SAID HUB AT SAID ONE SIDE OF SAID DRIVEN MEMBER, RADIAL DRIVING PORTIONS FORMED ON SAID HUB EXTENDING LONGITUDINALLY FROM SAID FLANGE AND PASSING THROUGH SAID APERTURE WALL RE-ENTRIES IN CLOSE FIT RELATIONSHIP, SAID SHORT CYLINDRICAL HUB PORTION BEING LONGER THAN THE THICKNESS OF SAID DRIVEN MEMBER, AND SAID FLANGE HAVING A CIRCUMFERENTIAL RIM PROJECTING FROM THE INNER FACE THEREOF AND ENGAGING SAID OTHER SIDE OF SAID DRIVEN MEMBER, SAID HOLLOW HUB HAVING SUFFICIENT RESILIENCE TO PERMIT PASSING SAID ROUND TAPERED PORTION THEREOF THROUGH SAID APERTURE WITHOUT PERMANENT DEFORMATION THEREOF AND SAID CIRCUMFERENTIAL RIM EXTENDING SUFFICIENTLY FROM THE INNER FACE OF SAID FLANGE TO RESULT IN SOME DISTORTION OF SAID FLANGE WHEREBY SAID SHOULDER AND SAID CIRCUMFERENTIAL RIM BEAR FIRMLY AGAINST THE OPPOSITE SIDES OF SAID DRIVEN MEMBER. 